For connecting homes and base stations with optical fibers and performing transmission and reception of optical signals, wavelength division multiplex type optical transmitting and receiving modules, using, for example, optical signals of a 1.3 μm band for uploading and optical signals of a 1.55 μm band for downloading, have been developed. An example of such an optical transmitting and receiving module is disclosed in Japanese Published Unexamined Patent Application No. H11-68705 (Patent Document 1).
This optical transmitting and receiving module has a flat substrate, and an optical branching waveguide is formed on the flat substrate. A groove is provided at a branching portion of the optical branching waveguide, and in this groove is disposed a dielectric multilayer film filter that branches input light into a transmitting direction and a reflecting direction according to wavelength. Also, a transmitting laser diode and a receiving photodiode are disposed on the flat substrate. The transmitting wavelength of the dielectric multilayer film filter is set to the received wavelength of the receiving photodiode, the blocking wavelength is set to the oscillating wavelength of the transmitting laser diode, and the transmitting laser diode and the receiving photodiode are disposed at opposite positions across the dielectric multilayer film filter.
Patent Document 1: Japanese Published Unexamined Patent Application No. H11-68705